Projecte de la Comissió Europea

Abstract

Strong-field physics is currently experiencing a shift towards the use of mid-IR driving wavelengths.
This is because they permit conducting experiments unambiguously in the quasistatic regime and enable
exploiting the effects related to ponderomotive scaling of electron recollisions. Initial measurements taken
in the mid-IR immediately led to a deeper understanding of photoionization and allowed a discrimination
among different theoretical models. Ponderomotive scaling of rescattering has enabled new avenues
towards time-resolved probing of molecular structure. Essential for this paradigm shift was the convergence
of two experimental tools: (1) intense mid-IR sources that can create high-energy photons and electrons
while operating within the quasistatic regime and (2) detection systems that can detect the generated highenergy
particles and image the entire momentum space of the interaction in full coincidence. Here, we
present a unique combination of these two essential ingredients, namely, a 160-kHz mid-IR source and a
reaction microscope detection system, to present an experimental methodology that provides an
unprecedented three-dimensional view of strong-field interactions. The system is capable of generating
and detecting electron energies that span a 6 order of magnitude dynamic range. We demonstrate the
versatility of the system by investigating electron recollisions, the core process that drives strong-field
phenomena, at both low (meV) and high (hundreds of eV) energies. The low-energy region is used to
investigate recently discovered low-energy structures, while the high-energy electrons are used to probe
atomic structure via laser-induced electron diffraction. Moreover, we present, for the first time, the
correlated momentum distribution of electrons from nonsequential double ionization driven by mid-IR
pulses